AddHeader and Detlais top Of the Word file

I am Using Fllowing method and Export Word File.I want to Add a  AddHeader and Detlais top Of the Word file.how to do it??
 
  protected void Button1_Click(object sender, EventArgs e)  
    {  
        ExportGridToword();  
    }  
    private void ExportGridToword()  
    {  
        Response.Clear();  
        Response.Buffer = true;  
        Response.ClearContent();  
        Response.ClearHeaders();  
        Response.Charset = "";  
        string FileName = "Vithal" + DateTime.Now +".doc";  
        StringWriter strwritter = new StringWriter();  
        HtmlTextWriter htmltextwrtter = new HtmlTextWriter(strwritter);        
        Response.Cache.SetCacheability(HttpCacheability.NoCache);  
        Response.ContentType ="application/msword";  
        Response.AddHeader("Content-Disposition","attachment;filename=" + FileName);  
        GridView1.GridLines = GridLines.Both;  
        GridView1.HeaderStyle.Font.Bold = true;  
        GridView1.RenderControl(htmltextwrtter);  
        Response.Write(strwritter.ToString());  
        Response.End();      
  
    }